Plum Island dodged another serious blow yesterday, as the much ballyhooed storm that struck our coast proved to be less than forecast. There was a period of several hours in which impressive waves hit the shore, but they were not nearly as large as the huge rollers that struck during a fierce storm two weeks ago that gouged out some significant chunks of dune.
Despite the construction of massive stone walls along the dune fronts, the overall picture in the area just south of the island center remains tenuous. Homes are clinging to a narrow strip of sand in this area. It’s a lean amount of land that serves as the barrier between the sea and the roads under which the island’s water and sewer lines are buried. If the stone walls are breached, there is nothing to stop another round of devastation like that which occurred last year, when six homes were consumed.
There are two observations we’ve made this winter.
One is that the usual migration of erosion hasn’t happened. Erosion along the island is often heavily influenced by a massive sandbar that lies just offshore. It serves as a barrier of sorts, and when it lengthens or shortens, the area of protected shoreline erosion moves with it. However, this year the area of erosion remains about the same as last year.
There are theories that suggest the size and length of this sandbar may be tied to the south jetty, located a mile or so to the north. It’s hoped that repairs to the south jetty, which have been ongoing off and on for about a year, would change the sandbar and the erosion dynamic. It appears that thus far it has not.
The other observation is that the fate of three old homes that have historically served as marking points along the beach have been heading in the wrong direction. The most prominent of these homes, the Bennett Hill House, has seen an enormous amount of erosion strike the 25-foot dune it sits on. It is now at the point where the front of the home hits precariously at the edge of the dune, something that has not been seen since the home was built in the 1880s.
Fifty yards to the north sat what was called the Buzzotta house, a home that figures prominently in old photos of the island center. It was lost five years ago. And about 100 yards to the south of Bennett Hill sits another old cottage that is also a prominent marker in beach photos; erosion has exposed part of its foundation.
Erosion has ebbed and flowed along this section of Plum Island for as long as photos have been around to document it, but the landward movement of dunes at these marker houses seems to be clear evidence that line is moving inland. What that means for the island overall is something that the experts will sort out. The Army Corps of Engineers has been engaging in a lengthy study of the Merrimack River mouth, the jetties and their impacts on the shoreline. Numerous professionals and well-educated amateurs have been studying these dynamics as well. And those who are interested in sea level rises have been documenting this carefully. The island is one of the most dynamic places for us to observe how our world is changing.
For now, the rock walls seem to be the salvation for the most imperiled stretch of Plum Island. We have a couple more months of bad weather to go; we hope that they will continue to hold.